In general, connection pins are made in strip form by stamping and folding electrically conducting metal sheet with each pin having a head terminated by a three-claw resilient clamp offset sideways and intended to fix onto the edge of a substrate, with two of the claws engaging one face of the substrate and with the third claw engaging the opposite face.
Terminal pads on the edge of a substrate for receiving said pins are generally constituted by two rectangular areas capable of being tinned and having the same width as the clamp on a pin, said areas being disposed to overlie each other on opposite faces at the edge of substrate at locations where the three claws of the clamp on a pin will grasp the substrate.
Strips of connection pins are mounted on the edges of a substrate while the substrate is still bare but after it has been tinned so that all of the components can be put into place thereon and then simultaneously reflow soldered. In other words, the pins are mounted on terminal pads which are coated with blobs of solder of thickness which is difficult to control and which is non-negligible in comparison with the thickness of the substrate. This gives rise to at least two drawbacks, with the first drawback being the difficulty of centering the three-claw clamp of a pin on a pad by virtue of the two blobs constituting a somewhat spherical shape, and the second drawback is that the blobs of solder on the pads are sometimes thicker than the elastic limit of the claws in a pin's clamp, thereby reducing the spring effect and preventing the claws of the clamp from returning to direct contact with the substrate during the reflow operation.
The object of the present invention is to combat these drawbacks which increase assembly time and which give rise to a high retouching rate.